In a tsp of oil saute onion tomato till it shrinks and raw smell leaves.
Add all the ingredients listed under 'to grind' in a mixer along with onion tomato. Sprinkle little water and grind it to a fine paste.
Soak tamarind in warm water(say 1/4 cup), extract pulp and keep aside. Heat remaining oil in the kadai add mustard seeds, allow it to splutter.
Clean fish, wash it well and add turmeric powder and set aside. Then add curry leaves, onion, garlic saute for 3mins then add tomatoes saute until raw smell leaves.
Then add the grinded paste, turmeric powder.
Add 1/4 cup water (adjust according to thickness) , required salt and allow it to boil for 15-20mins.
Add tamarind pulp and allow it to boil.
When oil separates add the cleaned fish pieces. Allow it to boil and the fish to cook well.
The fish will cook faster so be careful not to break the pieces.
Once the fish turns soft and the curry is well boiled and thick, oil will start collecting at the edges.
At this stage garnish with coriander leaves and switch off.
Give resting time for at least an hour before you serve. Serve hot with rice, tastes heavenly. Tastes best the next day or even after that :)